A subsidiary of the haulage firm Eddie Stobart has emerged as a leading contender in bidding for a new generation of criminal legal aid contracts that would deprive defendants of the right to choose their own solicitor.

Lawyers are planning protests outside parliament in opposition to the Ministry of Justice's proposals, which aim to cut fees, reduce funding of judicial reviews and save a further £220m out of the legal aid budget.

The row within the legal profession over the plans is intensifying. The head of Stobart Barristers has described traditional law firms who rely on legal aid as "'wounded animals waiting to die" and accused rival lawyers of sending his firm messages urging it to "Truck Off".

The MoJ's most controversial proposal is the introduction of competitive tendering in contracts to provide lawyers for defendants in criminal trials.

In order to guarantee winning firms receive a sufficient number of cases each year, the MoJ is proposing to remove the right of defendants funded by legal aid to select their own solicitor.

The arrival of Stobart Barristers last year has reinforced fears among the wider legal profession. Stobart operates by connecting clients directly to barristers, cutting out the need for solicitors.

Trevor Howarth, its legal director, said the firm would be bidding for the new criminal defence contracts. "We can deliver the service at a cost that's palatable for the taxpayer," he said. "Our business model was developed with this in mind.

"We at Stobart are well known for taking out the waste and the waste here is the duplication of solicitors going to the courtroom. At the moment there are 1,600 legal aid firms; in future there will be 400. At Stobart, we wouldn't use 10 trucks to deliver one product."

Howarth said he had received emails from solicitors with the heading "Truck Off". He added: "I have already taken calls from barristers [on our panels] who say they have been contacted by solicitors telling them they won't use them again if they take instructions from us."

On removing a defendant's right to choose their solicitor, Howarth said: "I don't think the lack of choice is damaging. [People are not] entitled to access justice with an open cheque. No one is stopping them paying for their own choice of solicitor."

Barristers and solicitors held a protest meeting in Manchester last month. Another protest meeting by lawyers is being organised for 22 May outside parliament.

Under the plans, defendants on legal aid will no longer be able to choose which lawyer represents them in a police station or a magistrate's court. They will still be able to choose which barrister represents them at crown court.

Paul Harris, president of the London Criminal Courts Solicitors' Association, warned that the quality of legal representation would decline. "How is anyone facing serious criminal allegations going to feel being represented by a haulage company?" he asked. "The individual will have no choice. The state will prosecute you and then choose your lawyer. By removing choice, providers will have less incentive to compete on quality. We will end up with far more miscarriages of justice."

The Bar Council, which represents barristers, has launched an online petition under the slogan "Say No to Cut Price Justice". Maura McGowan QC, chairman of the Bar Council, said: "It is against the public interest to introduce a system where legal services are provided on cost alone, by the lowest bidder, and not on quality … where you have no choice of who represents you."

Sadiq Khan MP, Labour's justice spokesman, told the Law Society Gazette: "No one wants a second-rate system where you are forced to accept whatever representation you are given regardless of quality."

An MoJ spokesperson said: "Quality-assured lawyers will still be available. Quality standards will be assessed as part of the tender process and we will ensure they are maintained by the lawyers who win contracts. We will continue to uphold everyone's right to a fair trial, but with £1bn a year spent on criminal legal aid we have to look again at how to deliver better value for every penny of taxpayers' money spent."